Prolactin messenger ribonucleic acid levels, prolactin synthesis, and radioimmunoassayable prolactin during the estrous cycle in the golden syrian hamster

Massa, John S.; Blask, David E.

doi:10.1016/0024-3205(90)90092-6

Cited by 2 publications

(6 citation statements)

References 22 publications

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“…In both studies, Prl levels increase on the afternoon of each day with a higher peak during the proestrous surge. Serum Prl levels increase dramatically during the latter part of diestrus II corresonding to the reported increase in estradiol levels in the female hamster [28], The Prl mRNA profile demonstrated dur ing this study agree quite well with that recently reported for hamsters [29] and rats [11]. Of special note is an identical dra matic fall in Prl message during the early afternoon of diestrus II for both rats and hamsters.…”

Section: Discussionsupporting

confidence: 80%

“…Immediately following this drop, Prl mRNA levels increase on the afternoon of diestrus II corre sponding to the time in which estradiol levels begin to rise, and again finally during the surge of estradiol on the afternoon of proestrous. Although we were unable to measure pituitary Prl content in this study, Massa and Blask [29] reported corre sponding increases in pituitary Prl hormone content with in creases in Prl message. The model proposed by these workers [29] for the hamster Prl surge is supported by our data.…”

Section: Discussionmentioning

confidence: 85%

“…Although we were unable to measure pituitary Prl content in this study, Massa and Blask [29] reported corre sponding increases in pituitary Prl hormone content with in creases in Prl message. The model proposed by these workers [29] for the hamster Prl surge is supported by our data. The rise in Prl mRNA on diestrus II and proestrus could contribute to the Prl proestrous surge.…”

Section: Discussionmentioning

confidence: 85%

“…There are few reports on the hormonal regulation of gonadotropin transcription. Utilizing the nuclear run-on technique, estrogen and progesterone have been reported to depress the transcrip tion of the a and FSHfl subunits in ovine pituitary cultures [29], while in another study estradiol has been shown to increase Prl transcription in the rat pituitary [28]. Nanomolar concentrations of LHRH increase transcription of the LH|) subunit and have no affect on mRNA levels in the cytoplasm of primary cells prepared from ovariectomizd female rats [31,32].…”

Section: Discussionmentioning

confidence: 99%

“…While Prl mRNA increases again dur ing the early hours of estrus, serum Prl is near basal levels. Massa and Blask [29] suggest that the shunting of newly synthe sized Prl into stored pools early on estrus is a mechanism whereby Prl can be released in adequate levels to stimulate cor pora lutea function following the mating stimulus. In the female hamster, estradiol levels fall late in proestrus and remain low throughout the following day of estrus.…”

Section: Discussionmentioning

confidence: 99%

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Serum Luteinizing Hormone, Prolactin, and Thyrotropin and Their Pituitary Subunit mRNA Levels during Proestrus in the Syrian Hamster

et al. 1991

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mRNA levels for α, luteinizing hormone β (LHβ), and prolactin (Prl) were examined during the hamster estrous cycle, with sampling most frequent (1-hour intervals) on the afternoon of proestrus. These transcripts encode the peptide subunits for the pituitary hormones LH and Prl which are necessary for reproductive function. Serum hormone levels of LH and Prl, analyzed by 24-hour periodic regression, exhibited a 24-hour periodicity on proestrus characterized by a large surge peaking at about 18.00 h. Combining the data for non-proestrous days of the cycle disclosed a rhythm with similar timing for LH and Prl. Thyroid-stimulating hormone (TSH) and TSHβ RNA profiles during hamster proestrus are reported for the first time. Serum TSH exhibited a pronounced peak coincident with that of the other hormones on proestrus. Because of variations at other times on the day of proestrus, however, a 24-hour periodicity was not manifested by regressional analysis. Combined non-proestrous serum TSH data also revealed no consistently timed regressional 24-hour periodicity. During proestrus, pituitary mRNA values for α, LHβ, and Prl simultaneously exhibited a rise from the lowest to the highest of all proestrous values in the 3–5 h prior to the time of the pre-ovulatory peak of circulating hormone concentrations. RNA for TSHβ exhibited an earlier, broader peak on proestrus. Periodic regression indicated a significant 24-hour rhythm for α mRNA in data pooled from non-proestrous days (acrophase 05.00 h) and for TSHβ mRNA on proestrus (acrophase 04.54 h). The necessity to pool the pituitary tissue from animals at particular time points limits the opportunity for statistical analysis of the mRNA levels. However, it is interesting that, on the afternoon of proestrus, the fluctuations of mRNAs for α subunit, LHβ, and prolactin were the widest for that day, were simultaneous, and preceded the hormone peak by 3–5 h; also, that the earlier rise of TSHβ mRNA on proestrus was detectable as a 24-hour rhythm. It is thus possible to hypothesize that a fluctuation in respective mRNA related to LH, Prl and TSH may occur in the hours preceding the proestrous surge of these hormones in the circulation, and may thus play a role in the hormonal surge.

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Serum Luteinizing Hormone, Prolactin, and Thyrotropin and Their Pituitary Subunit mRNA Levels during Proestrus in the Syrian Hamster

et al. 1991

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Sequence and Expression of Hamster Prolactin and Growth Hormone Messenger RNAs*

Southard

Sánchez‐Jiménez²,

Campbell³

et al. 1991

Endocrinology

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Complementary DNAs encompassing the complete protein-encoding regions for PRL and GH of the Syrian Golden hamster were sequenced and used as probes to examine the expression of hamster PRL and GH messenger RNA (mRNA)s. The complementary DNA (cDNA) for hamster PRL encodes a 226 amino acid preprotein which, by analogy to rat and mouse PRLs, is predicted to be processed to yield a 197 amino acid secreted protein. The hamster GH cDNA codes for a 216 amino acid preprotein predicted to yield a 190 amino acid secreted protein. Both hamster proteins are highly homologous to the corresponding rat and mouse hormones. For the secreted proteins, hamster PRL has 82% amino acid identity with rat PRL and 72% identity with mouse PRL. The rodent GH sequences are more strongly conserved, with 97-98% sequence identity between hamster, rat, and mouse GHs. The hamster hormones contain the highly conserved cysteine residues (six in hamster PRL and four in hamster GH) present in other mammalian PRLs and GHs. Neither hamster PRL nor hamster GH contains cysteine residues corresponding to the unique pair of cysteines present in hamster placental lactogen-II. The hamster PRL and GH cDNAs each hybridized to pituitary mRNAs of approximately 1 kilobase. Expression of hamster PRL and GH mRNAs was compared between 2 days of the estrous cycle (proestrus and estrus) and early, mid, and late pregnancy (days 5, 10, and 15). PRL mRNA levels in cycling hamsters were approximately 50% of those in pregnant hamsters. No other significant differences in PRL or GH mRNA levels were observed, suggesting that differences in circulating PRL and GH protein levels during the estrous cycle and pregnancy in the hamster are the result largely of factors other than changes in mRNA levels.

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Prolactin messenger ribonucleic acid levels, prolactin synthesis, and radioimmunoassayable prolactin during the estrous cycle in the golden syrian hamster

Cited by 2 publications

References 22 publications

Serum Luteinizing Hormone, Prolactin, and Thyrotropin and Their Pituitary Subunit mRNA Levels during Proestrus in the Syrian Hamster

Serum Luteinizing Hormone, Prolactin, and Thyrotropin and Their Pituitary Subunit mRNA Levels during Proestrus in the Syrian Hamster

Sequence and Expression of Hamster Prolactin and Growth Hormone Messenger RNAs*

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